Modify DescriptionArea to make hyperlinks live. Hyperlinks other than jar

resources just get sent off to the browser; jar resources get extracted into
temporary files, and those files' URLs get sent off to the browser.

I don't really like the handling of exceptions here, but I don't see a better
way around it. Trying to just declare hyperlinkUpdate() as throwing exceptions
fails because I'm overriding an abstract method that doesn't throw exceptions.
So, I need to throw a runtime exception when an exception happens; the stack
trace in the bug report shows that as the location of the exception so I
didn't want to just wrap all the code in the method in one big try/catch as
that reduces the information about where things broke.  So, bunch of try/catch
blocks around related operations.

swing/src/net/sf/openrocket/gui/components/DescriptionArea.java

@@ -1,16 +1,30 @@
 package net.sf.openrocket.gui.components;
 
 import java.awt.Color;
+import java.awt.Desktop;
 import java.awt.Dimension;
 import java.awt.Font;
 import java.awt.Rectangle;
 
+import java.net.URI;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+import javax.swing.event.HyperlinkEvent;
+import javax.swing.event.HyperlinkListener;
 import javax.swing.JEditorPane;
+import javax.swing.JOptionPane;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
 import javax.swing.ScrollPaneConstants;
 import javax.swing.SwingUtilities;
 
+import net.sf.openrocket.util.BugException;
+
 @SuppressWarnings("serial")
 public class DescriptionArea extends JScrollPane {
 	
@@ -65,7 +79,71 @@ public class DescriptionArea extends JScrollPane {
 		Font font = editorPane.getFont();
 		editorPane.setFont(font.deriveFont(font.getSize2D() + size));
 		editorPane.setEditable(false);
+		editorPane.addHyperlinkListener(new HyperlinkListener() {
+				public void hyperlinkUpdate(HyperlinkEvent e) {
+					if(e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
+						URI uri = null;
+						try {
+							uri = e.getURL().toURI();
+						}
+						catch (Exception ex) {
+							throw new RuntimeException(ex);
+						}
 						
+						// If the uri scheme indicates this is a resource in a jar file,
+						// extract and write to a temporary file
+						if (uri.getScheme().equals("jar")) {
+							
+							// get the resource
+							String uriString = uri.toString();
+							String resourceName = uriString.substring(uriString.indexOf("!") + 1);
+							final BufferedInputStream is = new BufferedInputStream(getClass().getResourceAsStream(resourceName));
+							
+							// construct filename from resource name
+							String prefix = resourceName.substring(1);
+							String suffix = null;
+							final int dotIndex = prefix.lastIndexOf(".");
+							if (dotIndex > 0) {
+								prefix = resourceName.substring(0, dotIndex);
+								suffix = resourceName.substring(dotIndex+1);
+							}
+							
+							// create temporary file and copy resource to it
+							File of = null;
+							BufferedOutputStream os = null;
+							try {
+								of = File.createTempFile(prefix, suffix);
+								os = new BufferedOutputStream(new FileOutputStream(of));
+							}
+							catch (Exception ex) {
+								throw new RuntimeException(ex);
+							}
+							of.deleteOnExit();
+							uri = of.toURI();
+
+							try {
+								int avail = is.available();
+								while (avail > 0) {
+									byte buffer[] = new byte[avail];
+									int bytesread = is.read(buffer, 0, avail);
+									os.write(buffer, 0, bytesread);
+									avail = is.available();
+								}
+							}
+							catch (Exception ex) {
+								throw new RuntimeException(ex);
+							}
+						}
+						
+						try {	
+							Desktop.getDesktop().browse(uri);
+						}
+						catch (Exception ex) {
+							throw new RuntimeException(ex);
+						}
+					}
+				}
+			});
 		if (!opaque) {
 			Color bg = new JPanel().getBackground();
 			editorPane.setBackground(new Color(bg.getRed(), bg.getGreen(), bg.getBlue()));